全文获取类型
收费全文 | 7882篇 |
免费 | 335篇 |
国内免费 | 173篇 |
专业分类
电工技术 | 190篇 |
技术理论 | 3篇 |
综合类 | 328篇 |
化学工业 | 741篇 |
金属工艺 | 139篇 |
机械仪表 | 191篇 |
建筑科学 | 362篇 |
矿业工程 | 93篇 |
能源动力 | 69篇 |
轻工业 | 294篇 |
水利工程 | 68篇 |
石油天然气 | 189篇 |
武器工业 | 23篇 |
无线电 | 500篇 |
一般工业技术 | 445篇 |
冶金工业 | 4080篇 |
原子能技术 | 20篇 |
自动化技术 | 655篇 |
出版年
2024年 | 6篇 |
2023年 | 49篇 |
2022年 | 108篇 |
2021年 | 95篇 |
2020年 | 101篇 |
2019年 | 83篇 |
2018年 | 92篇 |
2017年 | 135篇 |
2016年 | 126篇 |
2015年 | 143篇 |
2014年 | 165篇 |
2013年 | 251篇 |
2012年 | 257篇 |
2011年 | 276篇 |
2010年 | 253篇 |
2009年 | 233篇 |
2008年 | 240篇 |
2007年 | 232篇 |
2006年 | 266篇 |
2005年 | 216篇 |
2004年 | 134篇 |
2003年 | 121篇 |
2002年 | 119篇 |
2001年 | 78篇 |
2000年 | 97篇 |
1999年 | 218篇 |
1998年 | 1273篇 |
1997年 | 723篇 |
1996年 | 524篇 |
1995年 | 254篇 |
1994年 | 249篇 |
1993年 | 255篇 |
1992年 | 43篇 |
1991年 | 92篇 |
1990年 | 78篇 |
1989年 | 75篇 |
1988年 | 72篇 |
1987年 | 67篇 |
1986年 | 45篇 |
1985年 | 48篇 |
1984年 | 7篇 |
1983年 | 13篇 |
1982年 | 22篇 |
1981年 | 26篇 |
1980年 | 36篇 |
1978年 | 12篇 |
1977年 | 104篇 |
1976年 | 261篇 |
1975年 | 6篇 |
1955年 | 7篇 |
排序方式: 共有8390条查询结果,搜索用时 234 毫秒
1.
Zhen Hong Mingshan Xue Yidan Luo Zuozhu Yin Chan Xie Junfei Ou Fajun Wang 《应用聚合物科学杂志》2021,138(2):49657
With the continuous development of bionics, such as, geckos and virginia creeper with both superhydrophobic and super-adhesive, the surface wetting and super-adhesive properties of various porous materials have attracted extensive attention of the scientific and medical communities. Here, the honeycomb polyurethane (PU) porous films with strong adhesion were successfully prepared by microphase separation method and the effects of growth parameters on their microstructure and adhesive strength to ice were investigated. It was found that a high relative humidity (e.g., 100%) and a low solution concentration (e.g., 2%) facilitated the formation of ordered honeycomb PU porous films, and as-prepared PU pores with average pore diameter as small as 5 μm are better ordered and more uniform than these in related documents. Although the contact angle of water droplets on the surface of PU porous films increased from the premodification value of 85–130° to more than 160° after surface modification with polydopamine (PDA), the corresponding rolling angle remained approximately constant (180°), indicating that the surface of PU porous films has strong adhesion similar to geckos and virginia creeper. Furthermore, at lower temperature, the PU porous films exhibited the high adhesive strength of 142.13 kPa on ice, which was strongly dependent on the porous microstructures and surface compositions. The improved adhesive behavior to ice of honeycomb PU porous films modified with PDA provides new strategies for surface modification of materials and potential applications in medical domain. 相似文献
2.
Marcus Reppich Zdeněk Jegla Jakob Grondinger Yaovi Ouézou Azouma Vojtěch Turek 《化学,工程师,技术》2021,93(10):1581-1589
This study investigates the behavior of fruit and vegetable samples during drying. The experimental data are fitted to several different thin-layer drying models. Regression analysis is used to determine model parameters, while statistical indicators serve to evaluate the goodness of fit. The power function model gives the best fit for all examined samples. Based on this model, different drying and heat storage technologies can be combined to ensure that the required residual moisture content of an agricultural product is reached. It is demonstrated on the case of a specific Togolese processing plant that under favorable conditions, fossil fuel consumption can be decreased by 33 %. 相似文献
3.
4.
4号强热带风暴“碧利斯”造成突如其来的特大暴雨,降雨范围广,强度大,总量多,时间长,在宜章创下了之最,而且在湖南省也是罕见的。文章对“7·15”特大洪灾雨水情、灾情、抢险救灾存在的问题进行了分析和反思,并提出了防汛抢险的措施和对策。 相似文献
5.
6.
多功能杀菌剂的合成及其性能研究 总被引:7,自引:1,他引:6
在现有季铵盐类杀菌灭藻剂上增加一个脂键,连接一个有机酸基团,合成一种兼具阻垢缓蚀功能的新型工业水处理用杀菌灭藻剂(多功能杀菌剂),经一系列评价实验表明:新型杀菌剂是较理想的杀菌剂,在较低浓度下,对硫酸盐还原菌(SRB)及腐生菌(TGB)均有很好的杀灭效果,优于1227杀菌剂,同时还具有较好的缓蚀阻垢效果。 相似文献
7.
8.
R Belville SH Pollack JH Godbold PJ Landrigan 《Canadian Metallurgical Quarterly》1993,269(21):2754-2759
OBJECTIVE: To determine the number, distribution, determinants, and health consequences of occupational injuries among working adolescents in New York State. DESIGN: A retrospective, population-based analysis of New York State workers' compensation award data and the Annual Demographic File, a supplement to the US Bureau of the Census Current Population Survey. PARTICIPANTS: Adolescents, aged 14 through 17 years, who received workers' compensation awards for occupational injury from 1980 through 1987. MAIN OUTCOME MEASURES: (1) Numbers, types, and rates of occupational injuries in working adolescents by age, sex, industry, and occupation; (2) health consequences of injury, especially disability and death; and (3) secular trends in injury award rates. RESULTS: A total of 9656 adolescents were compensated for occupational injuries; 4201 compensated adolescents (43.5%) suffered permanent disability; 31 working adolescents died. The annual mean rate of compensated occupational injury was 28.2 per 10,000 adolescent workers. Rates were higher in males than in females and ranged from 8.2 per 10,000 in 14-year-old male workers to 46.8 per 10,000 in 17-year-old male workers. Highest rates by industry were seen in manufacturing (49.0/10,000 adolescent workers) and agriculture (46.2/10,000). Unskilled labor was the most dangerous occupation (52.3/10,000). CONCLUSION: Occupational injuries are a substantial and underrecognized contributor to the continuing epidemic of injury among adolescents. 相似文献
9.
10.
An extended pharmacokinetic/pharmacodynamic (PK/PD) model is presented, in which the effect of binding of the drug to plasma proteins and to tissue binding sites in a peripheral compartment, and nonspecific and receptor binding in the effect compartment are taken into account. It represents an extension of the classical Sheiner model, and the model proposed by Donati and Meistelman. The present model is characterized by the following parameters: Kue (exit rate constant of unbound drug from the effect compartment), Pue (ratio of the unbound clearances to and from the effect compartment), fue (fraction of drug in effect compartment that is not bound to nonspecific binding sites), Kd (equilibrium dissociation constant of drug-receptor binding), and Rtot (concentration of receptor binding sites in effect compartment). The rate of association and dissociation of the drug-receptor complex can be incorporated in the model. The influence of the pharmacokinetic parameters (V1, V2, fu, fu2, CLu10, CLu20, CLu12, CLu21) and the PK/PD model parameters (kue, Pue, fue, Kd, Rtot) on various dynamic parameters is analyzed. These include potency (single dose needed to produce 90% effect, ED90), constant infusion dosing rate needed to maintain a constant effect of 90%, time to maximum effect (onset time), and duration to 90% recovery. The neuromuscular blocking agent vecuronium is used as an example. It is shown that both potency and time course of action are strongly dependent on the ratio V1/fu, CLu10, kue, Pue (at equipotent doses the time course is not affected by Pue), fue, Kd, and Rtot (only if Rtot is high), whereas they are less affected by the ratio V2/fu2, CLu20, CLu12, and CLu21. In general, the model parameters affect the ED90 and the time course of action in the same direction, e.g., an increase of V1 results in an increase of ED90 and an increase of onset time and duration. However, the unbound clearance CLu10, the intercompartmental unbound clearance CLu12 and the receptor affinity Kd have an opposite effect on ED90 and the time course parameters, e.g., an increase of CLu10 results in an increase of ED90 and a decrease of onset time and duration. This effect may be responsible for the inverse relationship between onset time and potency of neuromuscular blocking drugs observed in animal experiments and clinical studies. We demonstrate that PK/PD analysis using the traditional effect compartment model (Sheiner model) results in an apparent value of keo, which is a function of kue, fue, Kd, Rtot, as well as the unbound drug concentration in the effect compartment Cue. On the other hand, the model proposed by Donati and Meistelman gives correct values of keo (equal to the product fue.kue), but the receptor affinity Kd and the receptor density Rtot obtained by this method are apparent values, which depend on fu, fue, and Pue. 相似文献